riley
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Posts: 9
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Post by riley on Sept 17, 2019 18:27:10 GMT
Greetings!
I feel I have now perused this forum enough to ask a question or two. There seems to be a good group of knowledge and experience here. Looking forward to becoming part of the discussions. Actually started over in the general section but thought I would try and participate in the technical section. As the title might suggest I am the proud new owner of a DR-1. Just got it home last night and attempted to run it. It does turn on but the start relay chatters (or buzzes) constantly. It does not trip on overload and the compressor does seem to be spinning but the control box is too noisy to listen for other refrigerator noises - like refrigerant moving. I did not let it run for longer than about a minute for fear of damaging something. I know the chattering relay is not normal.
I did download the repair manual for the DR machines and began reading up on the control circuits. I think I can figure out the start - run circuits and even perform a rudimentary test of the bellows circuit. I have the top on my bench - actually suspended between 2 benches so everything is accessible including the evaporator.
My skill set is heavy elctro-mechanical. I can read and trouble-shoot analog circuits pretty well. Used to work for IBM waaay back in the day repairing keypunches and the old gray-iron card sorters, interpreters, etc. So I can read complex schematics and I understand Ohms law enough to function in that world. I also just completed the restoration of a couple old BMW motorcycles - I did all the work myself including paint but except machine work on my jugs and hand pin-striping. What I am weak on is refrigeration. I understand it conceptually but have very limited experience and very few tools relative to that trade - although I do have a few friends who do.
I just think this is a very neat and nice looking little machine. I Want to get it running so I can have cold beer in my barn and get it looking nice. It is pretty complete including the offset top shelf (but no other shelves). It even has the original line cord, which is in surprisingly good shape. There is no indication it was ever re-built but I think it was re-painted. Hinges are tight. Latch seems to work correctly. All the plated parts seem to be in very nice shape. I don't see any indication that the sulfur dioxide has escaped but don't really know how to check.
Any advice as to common problems, practices, procedures, where to start, etc. would be very much appreciated. If I can get this thing running, I can clean it up and shoot a real nice coat of enamel on it and get it looking like new. I'll follow up with a few pics from google drive
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riley
New Member
Posts: 9
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Post by riley on Sept 17, 2019 23:17:03 GMT
Update:
I have a type D-1 control. I see there is an oil conditioner (heater) that operates any time the machine is plugged in. When I operate the main switch the unit does turn on. The starting relay chatters like I was giving a DC device AC current but it is definitely a 60 cycle AC machine. The start contact operates correctly and then the over-current heater gets hot and it trips as designed. I manually bypassed over-current trip to continue operating and opened the start contact manually after a couple seconds. I also grabbed the start relay to stop the noise. When I do that the over current heater does cool down and the compressor sounds normal. The start relay never de-energizes. I didn't do that for long - maybe 2 minutes. It seems like either there is an over-abundance of resistance in the running circuit or the compressor is drawing too much current. I did notice the compressor got pretty hot.
Can anyone explain how to remove the control assembly from the top. There is more wiring there that I would like to have access to. What should I expect for resistance across the running and starting windings
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Post by ckfan on Sept 18, 2019 0:55:14 GMT
I responded to your original thread about your starting issue. I’m not certain this is what is causing the issue but some members have had good luck with lifting the control off of its base by removing the four screws that hold it in and then cleaning the spring contacts underneath. Since you have a type D control I am not as familiar with those because I have only seen type E. I know that Travis has seen one on a unit identical to yours. I think there are a few differences in the start circuit relay. One thing I would not do is bypass the overload. If something is wrong that is causing it to heat up that needs to be addressed first so that motor damage doesn’t occur. It doesn’t take long to do damage. Hopefully some others can chime in but I would suspect dirty contacts right now. Go look at my post on your original thread to get a basic understanding of how you take a type E control up. I assume it is similar for a D.
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riley
New Member
Posts: 9
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Post by riley on Sept 18, 2019 3:35:42 GMT
Tried again after leaving it plugged in but switched off for a few hours. Still trips on overload. Checked the oil heater. 885 ohms across the coil. Seems to be ok. Took the control off the top. Not much in the way of contacts under there but I will clean them up. Off to bed now. It'll have to wait till tomorrow
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Post by coldspaces on Sept 18, 2019 13:10:23 GMT
You are going to burn it up if you bypass the overload and run it that long. You need to lift the control, find the three wires that go to the compressor and ohm out the two windings and check for a short to ground. The windings are only insulated with cotton, they can't take what modern ones will when the cotton is 80-90 years old.
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riley
New Member
Posts: 9
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Post by riley on Sept 20, 2019 13:01:14 GMT
I will have a chance to get back to this tomorrow. I will certainly check for shorts to ground on both run and start windings. I will also check to see that I do have resistance to be sure the windings haven't opened. Any idea what I should see for resistance across those windings? Does the service manual have the value of the start resistor? I didn't see it on my first pass but there is a lot of information there.
Then I will clean all the contact surfaces at the control box and put it back together. At that point it seems I will be working my way to the compressor motor and ultimately the compressor itself to find the source of the overload condition. I have not read the service manual that far yet but If I end up having to get into the compressor housing how much fun would that be? Just wondering how far I can go before this turns into a pretty ice box.
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Post by turbokinetic on Sept 20, 2019 13:41:44 GMT
I will have a chance to get back to this tomorrow. I will certainly check for shorts to ground on both run and start windings. I will also check to see that I do have resistance to be sure the windings haven't opened. Any idea what I should see for resistance across those windings? Does the service manual have the value of the start resistor? I didn't see it on my first pass but there is a lot of information there. Then I will clean all the contact surfaces at the control box and put it back together. At that point it seems I will be working my way to the compressor motor and ultimately the compressor itself to find the source of the overload condition. I have not read the service manual that far yet but If I end up having to get into the compressor housing how much fun would that be? Just wondering how far I can go before this turns into a pretty ice box. Hi Riley. They used several values of start resistors. If I remember, they were in the 3 to 6 ohm range.
Unfortunately, what you are describing is very likely a winding failure. The current for the main (run) winding goes through the start-relay coil. When the motor is not rotating, the main winding draws a lot of amps through the relay coil. This causes the start relay to pull in and engage the start winding. Once the motor is up to speed, the current draw through the run winding drops off, allowing the start relay to release and de-energize the start circuit.
In your case, the run winding current draw never falls below the level where the start relay turns off. This is causing it to buzz and keep trying to engage the start circuit. There are only a few possible causes of this. One is that the start resistor has been completely bypassed. If this were the case, your test of manually opening the start contacts would have allowed the motor to stay running indefinitely without the overload tripping.
The other possibility is that the motor winding contains shorted turns and/or multiple ground faults. This allows stray current paths to develop in the winding, resulting in high current draw and overheating.
If you find ground faults in the compressor, or the winding is shorted internally (high amp draw in spite of correct connections etc.) then you're looking at a major repair.
I've got to second what Coldspaces said; whatever you do; never run the compressor without the overload in the circuit. If something goes wrong, it can be destroyed in seconds. You'll need to connect a Kill-A-Watt meter or other current meter device to the power supply to see how many amps are being drawn.
Sincerely, David
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Post by birkie on Sept 20, 2019 15:28:30 GMT
On my DR-1, I see something like:
common-start 6.1
common-run 4.5
start-run 10
As far as the control is concerned, I think the type D control is like a DR tall control, but configured differently. So the coil that is making noise is a solenoid whereby the current through its coil flows through the run windings of the compressor. A large amount of current (normally, at startup) causes the weigh to be pulled up, which turns on the start contacts and gets the compressor moving. Once up to speed, the amount of current in that solenoid decreases, and the weight drops, opening the start contacts.
So in this case, enough current is flowing through the run windings to keep the solenoid activated. The DR controls can be a bit imprecise, so it could be the case that the run winding current is actually acceptable and the solenoid is being too sensitive. To test this theory, try physically knocking the solenoid back down (it jumps 'up' upon start) with a stick and see what happens. It might stay down, and the machine might happily run. Observe the watts or current when you do this and see if they're normal. If there's something wrong with the machine (either the windings, or physical binding), the watts will be high. Only after you've proven the machine is OK does it make sense to try adjusting the solenoid in the control so that it doesn't stay engaged.
edit: I had to take a break typing this for a meeting, so I didn't see David's reply come in. As you can see, there is a lot that can be possibly wrong.
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riley
New Member
Posts: 9
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Post by riley on Sept 23, 2019 11:28:50 GMT
Thank you, David. You have confirmed what seemed to make sense to me. Life got in the way this weekend so I have not had a chance to get back into this project. I do have an ammeter so I can measure the current draw once I get it back together. Birkie, thanks for the resistance measurements.
Hoping against hope, I guess that the compressor motor is OK. If not this will become an ice box for the foreseeable future. I'll clean it up and give it a fresh coat of paint and new gaskets. Maybe keep my eye out for another top.
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